56 Joel E. Abbott1 & Roger L. Sur2 1 Advanced Kidney Stone Center of the Americas, Chesapeake Urology, University of Maryland School of Medicine, Hanover, MD, USA 2 UCSD Comprehensive Kidney Stone Center, Department of Urology, University of California San Diego Health, San Diego, CA, USA Miniaturization of instruments, improved technique, and developing safety principles have led to ureteroscopy (URS) being a safe, effective option for stone therapy. With smaller‐diameter ureteroscopes, less traumatic tips, and improved techniques, iatrogenic complications have declined and are now less common. To avoid intraoperative complications from URS, the surgeon should be familiar with the various complications, their incidence, associations, and the appropriate treatment. We review the various complications associated with URS and the strategies for safe URS. The definition and reporting of complications varies widely. Commonly employed reporting systems segregate complications either by severity (minor and major) or by chronology (intraoperative and postoperative). No standardized classification has been adopted specifically for endoscopic complications. Many investigators utilize the Clavien‐Dindo classification; however, this system struggles to correlate the particulars of endoscopy. The Satava classification system attempted to address this deficit, with complications predicated on the intensity of management (Table 56.1) [1]. Several grading systems have emerged that are specific to the severity of ureteral wall injuries, which will be discussed later. Table 56.1 Clavien‐Dindo and Modified Sativa classification systems for surgical complications. The incidence of intraoperative ureteroscopic complications ranges from 0.5 to 20%, with 1.5–5% being major complications [2]. The majority of complications are minor and managed conservatively. Intraoperative overdistention of the bladder can lead to postoperative urinary retention and, on rare occasions, bladder perforation. Surgeons should note prostatic enlargement and pre‐existing outlet obstruction as contributing factors to postoperative retention. A small‐caliber Foley or red rubber catheter may be placed alongside the ureteroscope for bladder drainage. Monitoring bladder volume is particularly important for longer procedures performed without a ureteral access sheath (UAS). UAS use can mitigate this concern by creating a continuous irrigation flow system and bypassing the bladder. Accessing the ureter or kidney can be difficult. Failure to access the upper tract has been reported at 1.6–1.8% with flexible URS and up to 8% with semirigid ureteroscopy [1, 3, 4]. Associated risk factors are stones >15 mm and proximal stones [4]; anatomic features also contributing to operative difficulty include patient body habitus, intrinsic or extrinsic ureteral narrowing, stone impaction, ureteral edema or lesions (iatrogenic or pathologic), or genitourinary anatomy. Specific genitourinary anatomy that contributes to difficulty includes a cystocele, enlarged prostate, large intravesical median lobe, generalized edema, trabeculations, cellules, and abnormalities related to the ureteral orifice location, such as re‐implanted, ectopic, or duplicated ureters. Perhaps the safest option for the management of failed access is to abort the procedure with ureteral stenting if possible. Numerous difficulties can arise when attempting to access the ureteral orifice. Several techniques exist for orifice identification or cannulation. These include telescoping the wire through a ureteral catheter to improve direction and stability, converting to a straight or curved hydrophilic wire, emptying/filling the bladder, and manually reducing a cystocele or vaginal prolapse (e.g. vaginal packing). Ancillary instruments for complex access include a ureteroscope, flexible cystoscope, Albarran bridge with 70° lens, or specialty ureteral catheters (Figure 56.1). In the absence of complete ureteral obstruction, Methylene blue or Fluorescein can be administered intravenously to endoscopically visualize the effluxing ureteral orifice, and intravenous contrast can illuminate the distal ureter radiographically. Furosemide administration will expedite this process. Figure 56.1 Ureteral catheters. Source: Boston Scientific Corporation, Massachusetts, USA. Reproduced with permission of Boston Scientific. If the ureteral orifice is narrow or stenotic, it may not accommodate the ureteroscope. Dilation may be accomplished with tapered dilators or dilating balloons. Such dilation can be associated with perforation, stone extrusion, and avulsion [5]. To prevent such injury from unknown ureteral anatomy or ureteral stone, the ureter should be visualized using retrograde pyelography before dilating maneuvers. Prestenting the ureter (staged approach) is also an option. If difficulty is encountered passing a wire, several techniques may be employed. Retrograde ureterography can opacify the challenging anatomy and guide maneuvers. Telescoping the wire through a ureteral catheter and/or converting wires (e.g. combination polytetrafluoroethylene (PTFE)/hydrophilic wire, straight or curved hydrophilic wire) may be beneficial. If an obstruction or impacted stone is present, lubricating lidocaine jelly can be injected through a ureteral catheter positioned 1–2 cm beneath the stone/obstruction in an attempt to relax the ureteral smooth muscle and create separation between the stone and ureteral wall. To fluoroscopically visualize this maneuver, contrast agent can be mixed into the jelly. However, excessive injection force/pressure may injure the ureter, producing extravasation. Lastly, URS can be performed to endoscopically visualize the difficult ureteral segment and advance the wire under direct vision. If wire access is achieved but URS remains difficult, entering a narrow ureteral orifice and negotiating a difficult ureter can be accomplished using two wires (safety and working wire) and by maintaining maximal distance between the wires opening the ureter to “shoehorn” the scope (railroad technique). The scope should be rotated, as needed, to maintain scope orientation between the wires. If a stricture is encountered distal to a stone, it may be tapered or balloon‐dilated followed by case resumption. If the stricture is incised, a stent should be placed with stone treatment later to prevent stone fragments migrating into the disrupted ureteral wall. When deciding between the two techniques, the surgeon should note that balloon dilation provides faster, less forceful access through a narrowed ureter [6]. Because ureteroscopes have decreased in size, incidence of balloon dilation has decreased; however, UAS utilization has been reported to increase balloon dilation use [7]. Failure to advance UAS after balloon dilation is rare but merits termination of case and stenting [7]. Repeat URS can be performed 1–2 weeks later. An antegrade approach remains an option should retrograde fail. Equipment failure can preclude ureteroscopic success, with procedure abortion reported at a suspected underestimated 0.8% [1], while scope failure necessitating repair can be expected every 9–50 cases [8–11]. Most ureteroscope damage is iatrogenic, such as improper handling during instrumentation [12]. Most commonly, damage occurs to the working channel, especially the distal tip. The primary mechanism is passing instruments with the scope deflected or firing the laser within the scope’s working channel. The use of lithotrite alone predicts ureteroscope damage [12]. A major risk from laser use in a maximally deflected scope is damage to the channel at the point of maximum deflection due to energy released through microfractures in the quartz core material [13]. Stones should be repositioned to more favorable calyces prior to laser treatment. Backloading the ureteroscope over the stiff portion of a wire also risks internal channel punctures and flap creation. The most fragile portion of the scope is the active deflection unit. Excessive force/stress on the deflection mechanism expedites deterioration, typically occurring when the deflection circumference is greater than the renal pelvis size [9, 13]. Newer scopes with exaggerated active deflection may therefore shorten the interval between major repairs [14]. Duration of scope use inside the patient and patient’s body mass index were correlated with loss of downward deflection during use [15]. Lastly, applying excessive torque on the semirigid scope shaft leads to image distortion and scope failure [16]. To improve longevity, handling is critical: this includes maintaining the scope loosely coiled in transit, holding the handpiece with tip relaxed in a dependent position, straightening the scope into neutral position before advancing instruments through the channel, and using jelly or silicone lubricants to reduce frictional forces within the working channels. Ensuring both proximal and distal sections of the scope are synchronized mitigates torque‐twisting damage. Other recommendations include using UAS, nitinol devices, smaller holmium laser fibers, and laser tip visualization during use [17]. Proximal stone migration occurs in 3.5–12.2% of URS cases [1, 3, 4, 18, 19]. This increases operative/anesthesia time and may prevent case completion, subjecting a patient to additional anesthetic. Risks of proximal stone migration include initial proximal stone location, degree of ureteral dilation, pneumatic or electrohydraulic lithotrites, laser settings, and increased fluid irrigation. Antiretropulsion products are available to prevent proximal stone migration [1]. Stone migration into the ureteral wall occurs <1% in URS [20, 21]. Stone removal is technically difficult after extrusion, and further action should be done with caution and care. Intramural stone migration (“submucosal stone”) is stone extrusion through the ureteral mucosa, injuring the inner ureteral lining. This usually occurs during stone treatment and often with an impacted stone. Submucosal stones have been identified as predisposing to stricture formation and may become a nidus for stone growth [20, 21]. Stone fragments embedded within urothelium stimulate inflammation that may result in stone granuloma [22]. This raises concern during stone dusting techniques performed after ureteral perforation. Fragments may imbed within perforations as they pass down the ureter. Submucosal stones are typically diagnosed endoscopically as bulges from the inner ureteral wall, but can also be diagnosed with computed tomography (CT). Therapeutic approach is controversial because with observation a granuloma or stricture may occur, but extraction remains difficult and may result in further ureteral injury with worse long‐term sequelae. If a submucosal stone is identified during atraumatic URS (presumed chronic) laser excision followed by ureteral stent placement is recommended. Failure to remove stones requires long‐term follow‐up to ensure that a stricture does not occur. Extramural stone migration (“lost stone”) extruding past full thickness of the ureter is rare. This was more common prior to holmium, when higher power lithotrites were used. Risk factors for complete extrusion include improper endoscopic techniques, ureteral edema, poor blood supply of the ureteral segment, microtrauma to the ureteral segment, high intraluminal pressure from fluid irrigation, and outward compressive force on the stone into the ureteral wall from scope or instrument. The most serious sequelae are stricture and fluid extravasation, and retroperitoneal abscess can occur rarely if urinary tract infection (UTI)/bacteruria is present [23]. Stone retrieval should not be attempted [23, 24], but a ureteral stent should be placed due to perforation. Stone location should be documented, as future imaging studies may falsely diagnose ureteral calculus (Figure 56.2). Follow‐up upper tract imaging is indicated to exclude stricture formation and document extramural calculus position. Figure 56.2 Misdiagnosed ureteral stone. CT scan shows stone appearing to be in the mid left ureter; however; URS shows stone external to the ureter. Ureteral injury is the most frequent complication; however, it is typically managed with a ureteral stent. Delayed sequelae of significant ureteral injury and urine extravasation include prolonged ileus, urinary obstruction, urinoma, azotemia, fever, persistent flank pain, fistula formation, and sepsis [25]. Several validated classification systems have been developed for ureteral injuries (Table 56.2) [26–28]. Table 56.2 Classification of ureteral injuries. a American Association for the Surgery of Trauma. b Post‐Ureteroscopic Lesion Scale. Failed conservative management or high‐grade injuries require reconstruction. Timing of repair is either within first 5 days or deferred at least 6 weeks until resolution of acute periureteral inflammation. With a nephrostomy tube in place, retrograde and antegrade radiographic studies may be performed (Figure 56.3). Cystogram should also be performed prior to any potential bladder involvement in reconstruction. The optimal repair is based on injury location, degree of ureteral loss, and surgeon comfort/training (Table 56.3). Figure 56.3 Antegrade and retrograde fluoroscopic studies help to identify and quantify ureteral injury in preparation for repair. Table 56.3 Principles of ureteral reconstruction. Mucosal abrasion can occur to varying degrees in all URS procedures, especially with UAS use (Figure 56.4). Postoperatively, these abrasions may result in ureteral obstruction from edema or clotted blood [29]
Ureteroscopy Complications
Introduction
Classification
Clavien‐Dindo
Satava, Modified
Grade I: any deviation from normal postoperative course
Grade 1: incidents without consequences for the patient
Grade II: requiring pharmacologic therapy with drugs other than those allowed in Grade I
Grade 2a: managed intraoperatively with endoscopic maneuvers
Grade 2b: managed with retreatment (additional surgery) endoscopically
Grade III: requiring surgical, endoscopic, or radiological intervention:
Grade 3: managed with open surgery or laparoscopy
Grade IV: life‐threatening complication requiring intensive/critical care management:
Grade V: death
Suffix “d” may be added for disability, indicating follow‐up is needed after discharge to fully evaluate the complication
Intraoperative complications
Bladder distention
Failure to access the upper tract
Techniques for difficult ureteral access
Tight ureteral orifice
Difficult ureter
Equipment failure
Stone migration
Ascending/proximal migration
Ureteral stone extrusion
Intramural stone extrusion
Extramural stone migration: complete extrusion
Ureteral injury
Classification
Grade
Description
Management
AASTa
1
Contusion or hematoma without devascularization
Ureteral stent
2
<50% transection
Ureteral stent (or nephrostomy), may require surgical reconstruction
3
>50% transection
Ureteral stent (or nephrostomy), may require surgical reconstruction
4
Complete transection with <2 cm devascularization
Surgical reconstruction
5
Avulsion with >2 cm devascularization
Surgical reconstruction
Note: advance one grade for bilateral up to grade 3.
Traxer and Thomas
0
No lesion found or only mucosal petechiae
No Intervention required, consider ureteral stent 1–2 weeks
1
Ureteral mucosal erosion without smooth muscle injury
Ureteral stent 1–2 weeks
2
Ureteral wall injury involving mucosa and smooth muscle (periureteral fat not seen)
Ureteral stent 3–6 weeks
3
Ureteral wall injury involving adventitial perforation (periureteral fat seen)
Ureteral stent and/or nephrostomy, may require surgical reconstruction
4
Total ureteral avulsion
Surgical reconstruction
PULSb
0
No lesion or insignificant mucosal abrasions: contusions with minimal hematoma, mucosal moulding via guidewire
No intervention required
1
Superficial mucosal lesion and/or significant mucosal edema/hematoma: superficial bleeding/tears of the mucosa and/or mucosal edema or hematoma
No intervention required, consider ureteral stent (<1 week)
2
Submucosal lesion: deep tear of the mucosal and submucosal layer (ureteral integrity, no extravasation)
Short‐duration ureteral stent (1–2 weeks)
3
Perforation <50% (partial transection)
Moderate‐duration ureteral stent (3–4 weeks)
4
Perforation 50–99% (partial transection)
Long‐duration ureteral stent (6–12 weeks) (remaining tissue bridge enables conservative therapeutic attempt); likely to require surgical reconstruction
5
Complete transection
Ureteral stent or nephrostomy to temporize; surgical reconstruction is mandatory
Management
Ureteral injury
Reconstructive options
Proximal ureter
Small defect (<2 cm)
Ureteropyelostomy (dismembered pyeloplasty)
Ureteroureterostomy
Ureterocalycostomy
Large defect (>2 cm)
Renal pelvis flap (Scardino‐Prince vertical flap, Culp‐DeWeerd spiral flap)
Ureterocalycostomy (with renal mobilization)
Ureteroplasty with gastrointestinal segment (buccal, appendix)
Ureteral interposition with gastrointestinal segment (buccal, appendix, ileum)
Ureteroneocystotomy with Boari flap (Long)
Mid ureter
Small defect (<2 cm)
Ureteroureterostomy
Large defect (>2 cm)
Ureteroneocystostomy with Boari flap
Ureteroplasty with gastrointestinal segment (buccal, appendix)
Ureteral interposition with gastrointestinal segment (buccal, appendix, ileum)
Transureteroureterostomy
Distal ureter
Small defect (<2 cm)
Ureteroneocystostomy (reimplant): refluxing or nonrefluxing
Large defect (>2 cm)
Ureteroneocystostomy with psoas hitch
Transureteroureterostomy
Complete
Defect >10 cm
Ileal interposition graft
Renal autotransplantation
Mucosal abrasion
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